The result came 1:16 into the second round, when Silva (33-6) threw a left leg kick that Weidman (11-0) checked near his left knee.

Immediately, Silva fell to the ground in pain, prompting referee Herb Dean to waive an end to the fight. Replays showed Silva's shinbone snapped from the force of the collision.

The official result was a second-round TKO (injury) victory for Weidman. He claimed the 185-pound title in July in a stunning second-round knockout over Silva.

"That was the No. 1 one thing I got hit with in the first fight," Weidman said. "I worked a lot against guys with good leg kicks.

"I actually would think, 'If he's going to go hard on a ton of these kicks like he usually does, I could hurt him.' But it's still crazy."

Weidman, despite winning the first meeting, entered the fight a near 2-to-1 underdog to Silva.

The Brazilian icon, widely regarded as the greatest fighter in UFC history, had won 16 consecutive fights before losing his belt to Weidman this summer.

After taunting Weidman heavily during their first encounter, Silva was far more straight-laced in the rematch. He surrendered a takedown to the former collegiate wrestler 40 seconds into the fight, but scrambled back to his feet shortly after.

As the two tied up in a clinch, Weidman landed a short right hand near Silva's left temple that had him staggered.

As Silva fell to the floor, Weidman pursued with punches and landed in his guard. For the next three minutes, Silva kept his guard closed to prevent Weidman from passing -- but ate several elbows and right hands while stalling for the round to end.

Silva, 38, appeared to have recovered as he entered the second round. His movement was still intact -- as was his balance.

The leg kick and injury, however, happened in an instant.

It was the first time Silva has lost consecutive fights.

"He could come back, obviously, or it could be the end," UFC president Dana White said after the fight. "We'll have to see. He's going into surgery right this second."

Weidman, although on the winning end of both bouts against Silva, predicted he still might not get his due credit.

"Who knows?" Weidman said. "I'm so new in this sport. I'm 11-0 now and people can't fathom the fact I came in and beat Anderson Silva. I can understand where people are coming from but slowly and surely people will believe in me."

Weidman will likely face No. 1 middleweight contender Vitor Belfort in his second defense. Belfort, who was in attendance, had sympathy for Silva.

"It's sad, just the way it ended is sad," Belfort said. "We all have injury, I don't wish injury to anyone.